CFMC

Presentation

Modern epitaxial technologies allow for the realisation of semiconductor
nanostructures with simultaneous confinement of the electronic states and
of the light modes. This is the case of semiconductor microcavities, whose
elementary excitations are microcavity polaritons. These are two-dimensional
half-light half-matter quasi-particles arising from the strong coupling
between quantum well excitons and photons in a planar Fabry Perot resonator.

Their mixed light matter nature provides polaritons with unprecedented
fundamental properties. From their excitonic part, polaritons strongly
interact both with themselves and with the thermal bath of phonons. From
their photonic content, polaritons have a very small effective mass
(10-5 the free electron mass) and can be directly excited and observed
via their light absorption and emission. All these properties along with
their composite boson nature make polaritons very attractive to achieve
Bose-Einstein condensates (BEC) and to study quantum fluid effects in a
solid state system at high temperatures (5-300K). Moreover, the properties
of a polariton condensate, such as its density, phase and temporal and
spatial coherence, can be directly accessed by well developed optical
spectroscopy techniques in a large variety of structures and geometries.

The high crystallographic quality of the GaAs based microcavities along with
the refined etching techniques developed at LPN, allow for the Bose condensation
of polaritons in 2D, 1D and 0D structures, and open the way to the study of
coherent macroscopic phases, superfluidity, Josephson oscillations, soliton
formation, quantum turbulence studies, etc.

Reference contract : LIA
Coordinator, Partner(s) : F. Glas (LPN
),C2N leader(s): Frank GlasMain goals : Organize and develop scientific collaborations between the CNRS laboratories and the laboratories and institutes of the Russian Academy of Sciences based in Saint Petersburg in the domains of growth and study of the physical properties of nanostructures of compound semiconductors, and of compounds based on the latter. (2010-2017)

Reference contract : FP7-ITN-235114
Coordinator, Partner(s) : A. V. Kavokin (Universite De Southampton),C2N leader(s): Jacqueline BlochMain goals : The primary goal of this Network is to create a highly skilled body of young researchers capable of internationally competitive research in one of the most quickly developing areas of the modern physical science and technology. The main research objective of the CLERMONT4 network is to facilitate the exploitation of breakthroughs in polaritonics which occurred in 2006-2008. We shall focus on realisation of four prototypes of polariton devices: electrically pumped polariton lasers, micron size optical parametric oscillators, optical logic gates and cavity-based emitters of entangled photonic pairs. In order to realise these goals we have built a consortium of academic teams which have already given to Europe an enormous lead in the international competition with American and Japanese groups to realize practical polariton devices. Furthermore, we bring these academic teams together with an outstanding group of industrial partners capable of effectively driving through the translation of emerging promising new physical demonstrations into devices. (2009-2013)

ANR non thématiques

Quandyde : QUANtum DYnamics of exciton-polariton conDEnsates

Reference contract : ANR-11-BS10-001
Coordinator, Partner(s) : J. Bloch (LPN
), A. Bramati (LKB
), C. Ciuti (MPQ
), G. Malpuech (LASMEA
)Main goals : The four partners involved in the project propose to study the fundamental properties of polariton quantum fluids in resonators of different dimensionalities and different geometries. Moreover thanks to the high quality of GaAs based samples recently shown at LPN, they will develop innovative polariton devices to explore this physics. - The first task of Quandyde will be the study of propagating polariton condensates and their topological excitations. It is now feasible to observe the generation of solitons, of vortex lattices and explore quantum turbulence effects. Using samples with controlled disorder, we will explore the effect of disorder in the propagation –transition between localised and superfluid phases. - The second task of Quandyde will be the physics of new polaritonic devices. We want to observe the normal and chaotic Josephson oscillations, to build the first polariton interferometer, and to demonstrate polariton Bloch oscillations. Additionally, we plan to develop both from the theoretical and experimental point of view, the study of chains of micropillar cavities, a new paradigm for the physics of non-equilibrium Bose-Hubbard phases. (2011-2015)

Other National Projects

PEROCAI : Perovskite in microcavities

Reference contract : ANR Blanc
Coordinator, Partner(s) : E. Deleporte (LPQM
), J. Even (FOTON
), P. Audebert (PPSM
)C2N leader(s): Jacqueline Bloch, Sophie BouchouleMain goals : Vertical microcavities in the light-mater strong coupling are intensively studied due to the interest in coherent and stimulated effects in such systems as polariton lasing and Bose Einstein condensation in the solid phase. These effects have been recently demonstrated in “classical” inorganic semiconductors and most of the physics is done at low temperature. Until now, attempts to study these physical processes with molecular materials have failed.In this draft, we propose to use organic-inorganic molecular quantum wells inside a vertical microcavity to demonstrate stimulated effects at room temperature. The molecular quantum wells used in this study belong to the perovskite family. Because the strong coupling regime in vertical microcavities containing perovskites has been achieved at room temperature and because of the wide tunability of its exciton perovskite material is a good candidate to realize vertical microcavities and study these polaritonic effects. The physics of these new polaritons is unexplored. Therefore, polariton relaxation efficiency and dynamics will be studied. Finally, experiments designed to observe stimulated effects on these polariton states will be performed. Partners : LPQM-ENS Cachan (project leader), LPN, PPSM-ENS Cachan, FOTON-INSA Rennes (2010-2014)

Reference contract : Chaire Junior RTRA 2011-020T-BOSEFLOW1D
C2N leader(s): Alberto AmoMain goals : Quantum gases in reduced dimensionalities present new fundamental properties which strongly depart from their 3D counterparts. 1D systems are very attractive due to the fact that propagation properties are still present while interesting phenomena related to localisation-delocalisation, role of interactions and fermionisation effects in a boson condensate can be studied in a controlled environment. So far, much of the experimental and theoretical efforts in this direction have been undertaken in ultracold atomic condensates, which constitute text-book examples of bosonic condensates in equilibrium. While still much physics remain to be unveiled in this system, polariton boson condensates in semiconductor microcavities provide an excellent platform in the solid state for the study of a rich variety of quantum fluid effects in confined geometries. The main goal of this project is the study of the propagation, superfluidity and excitations in polariton condensates in 1D. These studies will be performed in collaboration with an experimental group working on 1D atomic Bose-Einstein condensates, profiting from mutual exchanges to understand the specifities of each system. (2011-2014)

MOSKITO : Peroskite Molecules in microcavities

Reference contract : RTRA-Triangle de la physique
Coordinator, Partner(s) : E. Deleporte (LPQM
), E. Deleporte (LPQM
)C2N leader(s): Sophie Bouchoule, Jacqueline BlochMain goals : The main objective of this project is to develop optical microcavities based on perovskite molecules emitting in the visible and UV range, and to carry out spectroscopic studies of these materials (with and W:O optical microcavity). The unique properties of the perovskite material (self-assembled as an organic quantum well) will be explored thanks to structural and spectroscopic cheracaterizations, in order to get a better understanding of the physics of these structures : nature of excitonic emission, phonon-exciton interaction, non-linearities in polaritonic emission, polaritonic laser emission … Duration : 24 months – Partners : LPQM-ENS Cachan (project leader), LPN. LPN will contribute in assembling the microcavity and in performing structural and time-resolved spectroscopic studies of the organic material (2009-2011)

Cavity polaritons in inorganic semiconductors are currently widely investigated, in particular in our group, because of their unique non-linear properties. Parametric oscillation with ultra-low threshold and polariton lasing (an analoguous to Bose condensation) is achieved. This opens a vast research field, both from the fundamental and applied point of view. In most of the cases, these experiments are performed at cryogenic temperatures. Recently the strong coupling regime has been demonstrated in semiconductor microcavities containing hybrid organic/inorganic active layer, based on perovskites. This new material presents very robust excitons enabling the observation of the strong coupling regime at room temperature and with record Rabi splitting. Within an ANR project in collaboration with the group of E. Deleporte at LPQM, ENS Cachan, we are currently exploring the potential of this new material.

A 2 year post-doctoral position is available at Laboratoire de Photonique et de Nanostructures (LPN) in Marcoussis, France. The position is related to a project dedicated to the generation of quantum correlated photons from multiple cavities and photonic microstructures. We want to take advantage of the strong excitonic non linearities in semiconductor microcavities containing quantum wells to implement a solid-state source of quantum correlated photons.

Scientific context: A fascinating property of bosons is their ability to spontaneously accumulate in a single quantum state, below a certain critical temperature. This so-called Bose condensation is at the origin of superconductivity, superfluidity of liquid helium and has also been observed with ultra-cold atoms. Recent studies have shown that semiconductor microcavities are a model solid-state system where Bose condensates can be obtained at temperatures as high as room temperatures. In these microcavities, the quasi-particules exhibiting bosonic behaviour are polaritons (quantum well excitons strongly coupled to the cavity optical mode). Beside their interest for fundamental studies, these polariton condensates could also provide low threshold sources of coherent light. Our group has recently demonstrated polariton condensation in GaAs/GaAlAs based microcavities . The advantage of this semiconductor material over other materials is that its growth and technological processes are very well controlled. This opens the unique possibilities for the development of innovative cavity geometries (single or coupled micropillars, photonic rings etc…) to investigate this new physics. Now that polariton Bose condensation has been clearly established, we are exploring the physics of these condensates, for instance superfluid propagation, behaviour under strong magnetic field or non-linear oscillations occurring when coupling two condensates.The thesis is part of these studies, led in collaboration with several theoretician groups, within the Clermont4 European network.

Spontaneous formation of polariton condensates in GaAs based microcavities